The present focus of treating human and industrial wastes is to employ mechanical systems such as activated sludge. There are certain advantages to this process, 1) reasonably compact as to the space it occupies; 2) treats and processes large flows; and 3) meets stringent E.P.A. requirements. Disadvantages, significantly, 1) expensive to build, operate and maintain; and 2) large user of electric power.
Traditionally, prior to reliance on mechanical systems, communities early on began to dispose of their sewage across rock filters, allowing natural processes such as algae, mosses, bacteria colonies to treat and reduce the polluted stream. A rock filter was simply a dug out basin filled with gravel. However, microbial colonies require oxygen as well as food supplied by the polluted stream, which these rock beds could not adequately supply.
Early in the twentieth century, trickling filters became popular. Sewage was sprayed over a holding basin filled with rock. This reduced the land area requirements, yet essentially the same filtering treatment process was used, moss, algae, complemented by microbes to reduce the pollution. Oxygen supply to the microbes increased yet still remained a limiting factor and as E.P.A. standards became more stringent, municipalities became to rely on the mechanical activated sludge system.
In the mid-twentieth century, scientists took an interest in wetland plants, observing that natural wetlands were eliminating pollution, pathogenic bacteria, and purifying ground-surface waters. A technology evolved whereby wetland plants were planted atop rock or sand beds and municipal primary sewage was admitted into these beds in varying configurations. Some waste streams were flowed across the surface of the beds, others as subsurface flows. Still a third began as surface flow, then vertically through the bed, filtering around the root system imbedded in the rock, sand substrata.
Wetland treatment successes depend on the ability of the macrophytes (wetland plants) to transport oxygen from the air to their root and rhizomes. Wetland plants such as cattails, bulrushes, reeds, canna lily, elephant ears, arrowhead, arrow arum, green taro, canex retriculata, schoenplectus and many others, have the common ability to transport oxygen from their leaves or stalks to their roots or rhizome areas through their vascular network called aerebchymas cells.
A healthy root system of the plant is maintained, even in extremely cold weather, by these cells' abilities to translocate oxygen to the roots even when the leaves or stems have died back as winter set in. It is oxygen supplied to the root systems which supports bacteria colonies responsible for reducing and purifying the wastewater stream.
“These vascular oxygen transferring cells occupy 60% of the plant structure. In addition to the microbial population that these plants support, the root systems act as filters and symbiotically produce metabolites which are a food source for microorganisms”, cited from B. C. Wolverton, scientists with the National Aeronautics Space Administration, 1986.
“Wetland plants reduce pollutants by the following processes: sedimentation filtration, adhesion and uptake. However, the primary, major mechanisms are respiration and fermentation by diverse colonies of microbes which break down organically derived pollutants into assumed harmless substances as CO2, N2 and H2O (water)”. Ecological Engineering 1435, page 6.
It is an object of the present invention to replicate the successful usage of wetland plants to treat polluted water in a terrestrial environment by the use of this apparatus to treat pollution of all types in watery environments such as rivers, lakes and all bodies of water. It is now therefore convenient to explore the operational usages and successes of wetland plants in treating primary wastewater in cultivated basins across Mexico, U.S., Canada, Europe and Korea.
The National Aeronautical Space Administration conducting 15 years of experimentation at its National Space Technology Lab in Southern Mississippi provided the following report presented by Mr. B. C. Wolverton in April 1986. Using reeds (phragmites communis), cattails (typha sp.) canna lily, arrowhead, arrow arum and green tare in cultivated (constructed wetlands) made the following observation:
“Biochemical oxygen demand substances were reduced an average 92.3%, in 24 hours, industrial chemicals, benzine reduced 99.98%, toluene reduced 99.985% p-xylene 99.94% all in 24 hours. Chloroform reduced 68% and tetrachlroethylene 75% also in 24 hours. The wetland roots then produce metabolites used as a food source by the microorganisms. These plants also add to the microbial filter capacity of removing toxic heavy metals and radioactive elements from the wastestream through the constructed (cultivated) wetland.” Wolverton described pollutant degradation as “microbial adaptation to using carbon sources from various organic chemicals by recruiting genes from existing plasmoids to make new plasmoids. These new plasmoids then encode for enzymes to convert the carbon source into compounds useful for energy and cell mass synthesis.”
The European Union in a three-year project, ARTWET, beginning October 2006 cultivated 11 wetland plots in Germany, France and Italy, testing reduction of herbicides, fungicides and insecticides complemented the N.A.S.A. observation, above, regarding the process of degradation as follows, “Macrophytes aerenchyme cells transport and deposit oxygen on the root surface one to four mm oxygen film, developing voltage potential Eh −250 to 500 mv. directly on root surfaces which allows aerobic heterotrophic micro-organisms to quickly grow and to degrade organic compounds as pesticides”. “Oxygen transfer, except in winter, is 100 to 200μ moles of O2 oxygen per hour per gram of dry root mass.” This amounts to approximately 0.0016 grams of oxygen per hour per gram of dry root mass.
In a review of microbial processes influencing performance of wetland plants, Ecological Engineering 1435, page 5 provides additional insight how the microbe process works, “Respiration and fermentation are the major mechanisms by which micro-organisms break down organically derived pollutants into harmless substances such as nitrogen gas, carbon dioxide and water. Furthermore, products as sulfides generated by some types of respiration can enable other known removal mechanisms such as precipitation and sequestration of heavy metals within the wetland matrix. In respiration, the microbes induce a transfer of electrons from a donor compound of a higher energy state (typically a carbon compound) to an electron acceptor of a lower state, using the energy difference for growth and reproduction—this process depends on oxidation-reduction conditions. High redox (oxidation-reduction) potential is associated with an oxidized environment and promotes aerobic processes as nitrification (reduction of nitrate compounds to NO3 and NO2). Low redox potential promotes anaerobic processes such as sulfate reduction and methanogenises, also reduction of NO3 and NO2 to nitrogen gas, manganese, iron (sulfates are reduced from soluble forms and become precipitates), in the anaerobic environment that exists distances greater than one to one and a half inches from the plant's root. As the distance from the root increases, the anaerobic conditions also increase and the redox potential in this area range from 100 mv to −350 mv.”
The following field studies of cultivated (constructed) wetlands from Southern California to Canada demonstrate that wetland plants can remove pollution of every sort from polluted waste streams in our environment. The San Diego Region Reclamation Agency at Santee, Calif. cultivated four test plots, each 696.6 square feet in area, under the direction of C. R. Goldman, R. M. Gersberg, B. V. Elkins, S. R. Lyons. Wetland plants in separate beds were bulrushes, cattails, reeds and an unvegetated or control bed.
Test period began August 1983 and ended December 1984. Primary wastewater was introduced flowing horizontally subsurface through a strata of gravel in each bed. The following average results were achieved: the bulrush bed removed 96% of biochemical oxygen demand, 94% of suspended solids, 96% of ammonia, B.O.D. and suspended solids were less than 10/10 mg/l, standard for advanced E.P.A. secondary treatment. Ammonia was less than 2 mg/l. The reed and cattail beds were less successful. Reductions were: B.O.D. 81%, 74%, suspended solids 86%, 91%, ammonia-nitrogen 79%, 54%, respectively. Input concentrations were 118 mg/l for B.O.D., 57.3 mg/l for suspended solids and 24.7 mg/l for ammonia.
The authors said “at this wastewater application rate, 20 acres of wetlands would be required to treat one million gallons/day.” Analysis and results of this test was reported in Water Resources Vol. 20, No. 3, pp. 363-368 (1986). The authors further commented as follows: “Of course studies were carried out in San Diego region of Southern Cal. where winter minimum water temperatures do not go much below 12 degrees Celsius (53.6° F.). Other investigators, however, have found that artificial (cultivated) wetlands are well suited for wastewater treatment even in moderately cold climates as Ontario, Canada where they can be operated year round (the wastewater flowing beneath the surface layer of ice) and produce an excellent effluent in all seasons.”
In a moderately cold climate of Iselin, Pa., a 7,875 square foot wetland basin flowing 6,800 gals/day horizontally, subsurface produced the following average pollution reduction in summer: biochemical oxygen demand 98%, suspended solids 90%, fecal coliform 100%, ammonia-nitrogen 93% and phosphorus 90%, comparable to the results achieved at the Santee, Calif. treatment plots. The operational periods at Iselin, Pa. began March 1983 and results tabulated to September, 1985. During the winter months, reductions of biochemical demand 96%, suspended solids 88%, fecal coliform 100% and ammonia-nitrogen 54%. It should be noted that Iselin used cattails and reed plants. Bulrushes that proved most effective in pollution reduction at Santee, Calif. were not used.
The observed average hydraulic flowing rate is approximately 0.42 gals/ft. square of wetland plant area. Despite the Iselin, Pa. hydraulic loading rate being 0.86 gals/ft. square of wetland plant area, twice the observed average, the results were impressive. It should also be noted that the longer pollutants are in contact with the root and rhizomes of these plants, the cleaner the water will become.
In a much colder climate of Listowel, Canada, using cattails in a 3,593 square foot cultivated marsh with municipal wastewater flowing at the rate of 4,367 gal./day across the surface of the cattail bed system, the average winter pollution reduction, January 1981 through April 1981, was as follows: biochemical demand 73%, suspended solids 84.3%, total phosphorus 73.5% and ammonia-nitrogen 22%.
There were several factors that limited the effectiveness of this wetland treatment:
1) The hydraulic flow rate was 1.22 gals. per square foot of wetland area, three times the observed rate of other similar facilities;
2) wastewater flowed across the surface of the wetland basin, limiting contact of the pollution stream with the root and rhizomes of the plants; and
3) the use of cattails as opposed to the use of bulrushes that proved so effective at Santee, Calif. test plots. Documentation of this plants' performance was entered January 1981 through August 1981. The summer months reduction at Listowel, May through August 1981: biochemical oxygen demand 75%, suspended solids 92%, total phosphorus 78.3% and ammonia-nitrogen 44%. Note again that, as the hydraulic rate increases, the contact time for pollutants to exposure to the microbes decreases, resulting in decreased reduction of pollutants.
As most fertilizers, urea, have high concentrations of nitrogen, their removal rates by wetland plants has been well documented and illustrated in the above examples. Chemicals such as herbicides, fungicides (pesticides) and insecticides are present in agricultural runoffs during the spring and summer growing season, and are pollution factors in rivers, though E.P.A. has not listed them as products with restricted applications. There has been limited research on reduction of these chemicals and, complicating matters further, there are so many different molecular and compound structures that are called pesticides and insecticides.
A European Union study called ARTWET, conducted years 2006 to 2008, reported a 54% reduction of pesticides by wetland plant cultivated basins. Cited by Springerin Environ. Chem. Lett. (2008), the author states “A lack of mitigation efforts through treatment leads to diffusion of pesticides throughout the environment with impact on wildlife and human health”. In Mississippi, using surface treatment along a 50 meter vegetated ditch, pesticide reduction of 99% was reported. Shultz and Peale reporting in J. Environmental quality 30: 814, also noted in Springer, Environ. Chem. Lett. (2008), that “a reduction of toxicity greater than 90% was achieved in South Africa.” These authors also noted that “a fruit orchard runoff into a 1.1 acre reed bed resulted in 90% reduction of aqua phase insecticide and particulate insecticide was removed 100%.”
Excellent results were realized in reducing pesticides using wetland plants by using Coriolus Versicolor, Hypholoma Fascioulare, Stereum Hersutum. In 42 days, diuron atrazine, terbuthylozene were reduced greater than 86%. After the wetland plants matured for two years, the herbicide, atrazine was reduced by microbial action in seven days.
The recommended flow velocity is one foot per second. Shultz and Peale comment further, “amount of pesticide carried in surface water runoff varies from 1 to 10 percent. Though this percentage is only a fraction of the applied chemical, the effects are high enough to exhibit biologically relevant effects. Concentrations as high as 300 mg/l have been reached.”
Pharmaceuticals and health care products are making an increasing appearance in drinking water. These are generally not removed in water treatment plants. The Korean Institute of Science, in collaboration with Southern Nevada Water Authority, issued findings in 2008 on removal rates of pharmaceuticals with the use of wetland plants. Thirty micropollutants including pharmaceuticals, endocrine blockers and personal care products were tested at the Damyang waste water treatment plant.
A constructed (cultivated) wetland, planted in cattails, 16,499 square feet of area treating 63,517 gals./day, tested nine pharmaceuticals found in high concentrations in the waste stream. Waste water stream was introduced in horizontal, subsurface flow and after six hours, five of the nine pharmaceuticals treating hypertension, convulsion, inflammation and infection were reduced, ranging from 65% to 98%. An anti-infection sulfamethexacole was reduced 30%. Delantin, an antiepileptic reduced 5% in May testing, 70% reduction in August, Diazepain, a tranquilizer reduced 6%, fire retardant reduced 10%.
As described earlier, microbial treatment in moderately cold climate of Pennsylvania and colder climate of Canada have successfully treated and reduced polluted wastewater streams. Allen et al. report in Journal Env. Quality, 31, pp. 1010-1016 “that diurnal oxidation-reduction by macrophytes (wetland plant) corexretriculates, and schoenplectus (was successful) at 4 degrees Centrigrade (39 degrees F.).
There does not exist a more versatile, successful and natural means of removing polluting wastestreams containing human, animal wastes, pesticides, fungicides, insecticides, fertilizer, urea, ammonia, dissolved heavy metals, radioactive metals, industrial chemicals and pharmaceuticals as this apparatus herein described from all bodies of water such as rivers, lakes, streams or port areas.
Wetland plants, bulrushes, cattails, etc. survive in marshes under water environment by translocating air to its root system. Oxygen leaking from the roots support colonies of bacteria which consume, treat and degrade a wastewater stream (municipal).
My prior U.S. Pat. No. 5,337,516, hereby incorporated in its entirety by reference, was designed to eliminate practically all media from the wetland basin, thus permitting unrestricted growth of the plant root and rhizome system, greatly reducing the land area needed to treat comparable flow of waste water to approximately one fourth to one fifth the size presently required in existing systems. Thus, less land treated more waste water, making this an attractive and cost effective means of treating municipal and industrial waste water in quantities of one million gallons per day and more. It eliminates the necessity of pretreatment as the entire floor of the basin can now be utilized as a receiver for the settlable solids, as the solids media that once occupied the entire basin, is now absent. The absence of solid media means that raw waste water can be directly admitted into the basin without the necessity of building a primary tank. The size or floor area of the wetland basin is on the order of 100 times greater than that of a primary tank. Hence, it is possible that this greatly enlarged floor area of the basin can be utilized to reduce or degrade settled solids through anaerobic and facultative bacterial action whereas by contrast, the floor area of the primary tank being smaller and not designed for treatment but only for collection purposes, is an expensive necessity when a basin for wetland basin is filled with solid media, but is not a necessity when a basin for wetland plants can be designed and operated without such a solid media. As a great deal of the settled solids are treated and reduced on the wetland basin floor, further treatment and reduction facilities, such as anaerobic or aerobic digesters can be downsized to less than half in size and cost as those that would otherwise be required using the present technology.
The apparatus, and process of my prior patent was intended to take wetland plants that have no natural capacity to float in water but are rooted to the bottom of wetlands, swamps, etc. and to create for them an artificial floating habitat. This is accomplished by constructing a basket or container which, in addition to a wetland plant, will contain rich earth, humus, clay, and among other options, activated carbon, charcoal, sand, burned and unburnt wood, which materials act as filters and assist the weighted matter to float better in the waste water to be treated and also basically to serve as a life support system to the wetland plant. In addition the basket or container will be attached to floats that will better enable the wetland plant to float in the waste water basin.
Each wetland plant habitat or container can preferentially be attached to others in a row by means of cables or ropes which are in turn anchored to posts along the perimeter of the basin. This will allow the operator of the basin to winch the cable or rope over to the side of the basin to remove or add additional plants and life support systems and then reintroduce them back into the basin.
The basket material may preferentially be any material supported by some rigid frame such as webbed construction so that the plant roots and rhizomes may grow through the basket into the waste water filled basin with life support material consisting of earth, clay, humus and other materials as described above. The basket material should be sufficiently open weave and porous to permit free flow of waste water into the plant habitat.
The plant container can preferentially also contain an adjustable floor so that it defines the limits of the root system that can grow downward toward the floor of the basin. As the root and rhizome area of the plants generate an aerobic environment, the operator of the basin can, by varying the vertical placement of the adjustable floor, increase or decrease the aerobic and anaerobic zones within the basin. When the basin depth is increased, perhaps four or five feet or even more, the amount of waste water in the basin for treatment is thereby also increased. The operator of the basin has the option to lower the adjustable floor thereby permitting and allowing the plant roots and rhizomes to grow vertically expanding the volume within the basin that will treat the polluted water within it, aerobically.